Vitamin D Supplementation Trial in People at Risk of Type 2 Diabetes
EUDRACT number – 2009-011264-11
This trial investigated whether giving vitamin D to people who are at risk of diabetes delays or prevents the development of diabetes. The full title of the study is: ‘A randomized, double blind, placebo controlled, phase II, multi-centre study to investigate the effects of vitamin D2 or D3 supplementation on metabolic parameters in people at risk of developing type 2 diabetes’.
Vitamin D is a natural substance produced in our skin when it is exposed to sunlight. It is also present in some foods. Vitamin D is essential for healthy bones. However recent research shows it may also have other benefits including preventing diabetes, heart disease, some cancers, and infections, but this is not yet proven and needs further research. Many adults (especially from ethnic minority groups) do not have enough vitamin D for good health.
This trial examined the effects of vitamin D in preventing or delaying the development of diabetes. Vitamin D comes in two forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Diabetes develops when the body is unable to handle sugar normally. This leads to high sugar levels in the blood which then damages various organs in the body. Diabetes is a leading cause of kidney damage, blindness, heart attacks and strokes. The number of people developing diabetes is increasing in the UK, especially among some ethnic groups.
The Vitamin D Supplementation trial was set up to investigate the effect of vitamin D supplementation in people at risk of diabetes to determine whether oral supplementation can lead to an improvement in glycaemia and related metabolic abnormalities. In collaboration with Queen Mary University London, we conducted a double-blind, randomised, placebo-controlled trial to assess feasibility, acceptability and effects on metabolic risk of high dose vitamin D2 or vitamin D3 supplements (four doses of 100,000 IU), or placebo over four months in people with non-diabetic hyperglycaemia. A total of 342 adults at risk of developing diabetes (either defined by the Cambridge Risk Score or by impaired glucose tolerance or impaired fasting glucose or non-diabetic hyperglycaemia, assessed by HbA1c) were recruited, 172 of whom were recruited through the Fenland study, and the rest recruited in London. The primary outcome measure was change in glycated haemoglobin level between baseline and 4 months. Secondary outcomes measures included blood pressure, anthropometry, lipid levels, apolipoproteins, highly sensitive C-reactive protein, parathyroid hormone and safety of supplementation.
The trial was conducted at two sites – the Clinical Research Facility at the Medical Research Council’s Epidemiology Unit at Addenbrooke’s Hospital in Cambridge, and at the Clinical Research Centre at the Royal London Hospital in Whitechapel. The chief investigator of the trial is Professor Graham Hitman at Queen Mary University London, and the Cambridge investigators are Dr Nita Forouhi (lead investigator) and Dr Simon Griffin.
Data collection complete, and analysis and publication are on-going
The study was co-led by the Unit and Queen Mary University, with shared custodianship of data and samples.
The funding for this trial is from the Medical Research Council core funding and Tower Hamlets Primary Care Trust, London.
A detailed explanation of the approved statistical analysis plan can be found at: Vitamin D Trial Analysis Plan September 2012